In the financial community, securities and commodities are usually traded using a private line trading network between brokerage houses, banks, and other trading partners. A brokerage house, for example, typically has one or more trading rooms coupled to a large number of telephone lines, usually private lines, going to its trading partners. A trading room may include any number of trading stations each including a key telephone known as a "trader turret" which provides key line access to a large number of the incoming lines. A large trading room can easily trade securities and commodities at the rate of millions of dollars per second.
A typical trading transaction involves a rapid series of short telephone conversations to locate traders having the desired security for sale at the best price. A typical call lasts ten seconds and there may be on the order of five calls per minute during the course of a single transaction. Private line key telephone systems provide immediate access and are preferred for the rapid, multi-call communications involved in most financial transactions.
Manual dialing is much too slow and cumbersome to be seriously considered in the hectic environment of financial trading. Auto dial systems where a single key actuation sends dial tones or pulses to a central office switch are also too slow for most trading operations since dial pulse systems usually take about eighteen seconds to connect, whereas tone systems usually take about fourteen seconds to connect. Private lines provide the desired immediate communication, but are much more expensive than switched lines.
The trader turret work stations are specially designed to suit the needs of a financial trader. The line key assignments on the console are a personal matter and may change as market conditions change. Typically a trader will want the most frequently called trading partners to appear at a specific line key and at specific locations on the console so that, in most cases, it is not necessary to take time to read the legends associated with the keys. The console must indicate the line status for all lines available at the console so the trader can tell which lines are in-use, on hold, ringing, or free. The console must also indicate the active line at the console so that the trader can always confirm the identity of the trading partner on the line.
An auto-dial line is not compatible with normal trader turret operations. With a switched line the central office switch selects the first available trunk to the trading room which means that the call from a particular trading partner can come in on a number of different lines. As a result, the call can appear at different locations on the trader turret which is generally unacceptable to traders. In addition, as previously mentioned, auto-dial lines take too long to complete a connection.